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Adherent cultured cells are widely used biological tools for a variety of biochemical and biotechnology applications, including drug screening and gene expression analysis. One critical step in culturing adherent cells is the dissociation of cell monolayers into single-cell suspensions. Different enzymatic and non-enzymatic methods have been proposed for this purpose. Trypsinization, the most common enzymatic method for dislodging adhered cells, can be detrimental to cells, as it can damage cell membranes and ultimately cause cell death. Additionally, all available techniques require a prolonged treatment duration, typically on the order of minutes (5-10 min). Dissociation of cells becomes even more challenging in microfluidic devices, where, due to the nature of low Reynolds number flow and reduced mixing efficiency, multiple washing steps and prolonged trypsinization may be necessary to treat all cells. Here, we report a novel acoustofluidic method for the detachment of cells adhered onto a microchannel surface without exposing the cells to any enzymatic or non-enzymatic chemicals. This method enables a rapid (i.e., on the order of seconds), cost-effective, and easy-to-operate cell detachment strategy, yielding a detachment efficiency of similar to 99% and cellular viability similar to that of the conventional trypsinization method. Also, as opposed to biochemical-based techniques (e.g., enzymatic), in our approach, cells are exposed to the dissociating agent (i.e., substrate-mediated acoustic excitation and microstreaming flow) only for as long as they remain attached to the substrate. After dissociation, the effect of acoustic excitation is reduced to microstreaming flow, therefore, minimizing unwanted effects of the dissociating agent on the cell phenotype. Additionally, our results suggest that cell excitation at acoustic powers lower than that required for complete cell detachment can potentially be employed for probing the adhesion strength of cell-substrate attachment. This novel approach can, therefore, be used for a wide range of lab-on-a-chip applications.

Polyelectrolyte microcapsules (PEMCs) have biocompatible microcompartments. Therefore, PEMCs are useful for applications in cosmetics, food, pharmaceutics, and other industries. The fabrication of PEMCs often involves the use of harsh chemicals or cytotoxic organic phases that make biomedical applications of the microcapsules challenging. In this report, we present an all-aqueous droplet microfluidics platform for the generation of magnetic PEMCs. In the platform, we use an aqueous-two-phase system (ATPS) of polyethylene glycol (PEG) and dextran (Dex), to generate water-in-water droplets, which are magnetically functionalized with ferrofluid. Strong polyelectrolytes (PEs) with opposite charges are used in each ATPS phase. We make emulsion templates of magnetic Dex, containing the polycations, in a continuous phase of PEG. We then apply a magnetic field to move the magnetic droplets to a second PEG phase, which contains the polyanions. By careful tuning of the fluxes of the two PEs in their respective phases, we trigger the formation of a shell at the droplet interface. Owing to the presence of the ferrofluid, the resulting microcapsules are magnetically responsive. We show that the magnetic PEMCs are capable of passive release of large pseudo-drugs as well as triggered release using external stimuli such as osmotic shock and pH change. We expect that magnetic PEMCs from this biocompatible all-aqueous platform will find utility in the fabrication of functionalized drug carriers for targeted drug delivery.

This work describes for the first time the fabrication and characterization of multicomponent interpenetrating networks composed of collagen I, hyaluronic acid, and poly(ethylene glycol) diacrylate for the 3D culture of human neural stem cells, astrocytes, and microglia. The chemical composition of the scaffolds can be modulated while maintaining values of complex moduli within the range of the mechanical performance of brain tissue (∼6.9 kPa) and having cell viability exceeding 84%. The developed scaffolds are a promising new family of biomaterials that can potentially serve as 3D in vitro models for studying the physiology and physiopathology of the central nervous system.

Microdroplets have been utilized for a wide range of applications in biomedicine and biological studies. Despite the importance of such droplets, their fabrication is associated with difficulties in practice that emerge from the incompatible nature of chemicals, such as surfactants and organic solvents, with biological environments. Therefore, microfluidic methods have recently emerged that create biocompatible water-in-water droplets based on aqueous two-phase systems (ATPS), most commonly composed of water and incompatible polymers, dextran (DEX) and polyethylene glycol (PEG). However, so far, DEX- and PEG-based water-in-water droplet generation schemes have been plagued with low throughput, and most systems can only generate DEX-in-PEG droplets; PEG-in-DEX droplets have been elusive due to chemical interactions between the polymers and channel walls. Here, we describe a simple approach to generate water-in-water microdroplets passively at a high throughput of up to 850 Hz, and obtain both DEX-in-PEG and PEG-in-DEX droplets. Specifically, our method involves a simple modification to the conventional microfluidic flow focusing geometry, by the insertion of a microneedle to the flow focusing junction, which causes three-dimensional (3D) flow focusing of the dispersed phase fluid. We observe that the 3D flow focusing of the dispersed phase enables excellent control of droplet diameters, ranging from 5 to 65 µm, and achieves a high throughput. Moreover, we report the passive microfluidic generation of PEG-in-DEX droplets for the first time, because in our system the 3D flow focusing of the disperse phase separates the disperse PEG phase from the channel walls, negating the commonly observed wall wetting issues of the PEG phase. We expect this microfluidic approach to be useful in increasing the versatility and throughput of water-in-water droplet microfluidics, and help enable future biotechnological applications, such as microparticle-based drug delivery, cell encapsulation for single cell analysis, and immunoisolation for cell transplantation.

In this study, a novel alumina-covered graphene oxide/polyimide (AlGO/PI) nanocomposite was developed as an anticorrosion coating material. The hydroxyl groups on GO reacted with aluminum isopropoxide via a sol-gel process to yield AlGO nanosheets. The characterization and structure were confirmed by Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and field emission transmission electron microscopy. Subsequently, GO and AlGO were incorporated into a PI matrix, leading to the formation of GO/PI and AlGO/PI nanocomposites. Well-dispersed AlGO nanosheets in the PI matrix acted as effective additives to enhance the water barrier properties of GO/PI (58 g/(m2·day)) and AlGO/PI (43 g/(m2·day)) coatings. Most importantly, the resultant AlGO/PI films exhibited excellent optical transparency (>75%) and anticorrosion properties. Electrochemical measurements of corrosion potential, polarization resistance, and corrosion current as well as electrochemical impedance spectroscopy confirmed that the AlGO/PI nanocomposites exhibited better anticorrosion properties than GO/PI nanocomposites. This is likely because the insulating layer of alumina on GO can isolate the charge transfer pathway between GO and the metal substrates, leading to improved anticorrosion behavior.

Loss of apical-basal polarity and activation of epithelial-mesenchymal transition (EMT) both contribute to carcinoma progression and metastasis. Here, we report that apical-basal polarity inhibits EMT to suppress metastatic dissemination. Using mouse and human epithelial three-dimensional organoid cultures, we show that the PAR-atypical protein kinase C (aPKC) polarity complex inhibits EMT and invasion by promoting degradation of the SNAIL family protein SNAI1. Under intact apical-basal polarity, aPKC kinases phosphorylate S249 of SNAI1, which leads to protein degradation. Loss of apical-basal polarity prevents aPKC-mediated SNAI1 phosphorylation and stabilizes the SNAI1 protein to promote EMT and invasion. In human breast tumour xenografts, inhibition of the PAR-complex-mediated SNAI1 degradation mechanism promotes tumour invasion and metastasis. Analyses of human breast tissue samples reveal negative correlations between PAR3 and SNAI1 protein levels. Our results demonstrate that apical-basal polarity functions as a critical checkpoint of EMT to precisely control epithelial-mesenchymal plasticity during tumour metastasis.

Biological research and many cell-based therapies rely on the successful delivery of cargo materials into cells. Intracellular delivery in an in vitro setting refers to a variety of physical and biochemical techniques developed for conducting rapid and efficient transport of materials across the plasma membrane. Generally, the techniques that are time-efficient (e.g., electroporation) suffer from heterogeneity and low cellular viability, and those that are precise (e.g., microinjection) suffer from low-throughput and are labor-intensive. Here, we present a novel in vitro microfluidic strategy for intracellular delivery, which is based on the acoustic excitation of adherent cells. Strong mechanical oscillations, mediated by Lamb waves, inside a microfluidic channel facilitate the cellular uptake of different size (e.g., 3–500 kDa, plasmid encoding EGFP) cargo materials through endocytic pathways. We demonstrate successful delivery of 500 kDa dextran to various adherent cell lines with unprecedented efficiency in the range of 65–85% above control. We also show that actuation voltage and treatment duration can be tuned to control the dosage of delivered substances. High viability (≥91%), versatility across different cargo materials and various adherent cell lines, scalability to hundreds of thousands of cells per treatment, portability, and ease-of-operation are among the unique features of this acoustofluidic strategy. Potential applications include targeting through endocytosis-dependant pathways in cellular disorders, such as lysosomal storage diseases, which other physical methods are unable to address. This novel acoustofluidic method achieves rapid, uniform, and scalable delivery of material into cells, and may find utility in lab-on-a-chip applications.

An approach for nanoscale 3-D tomography of organic carbon (OC) and associated mineral nanoparticles was developed to illustrate their spatial distribution and boundary interplay, using synchrotron-based transmission X-ray microscopy (TXM). The proposed 3-D tomography technique was first applied to in situ observation of a laboratory-made consortium of black carbon (BC) and nanomineral (TiO2, 15 nm), and its performance was evaluated using dual-scan (absorption contrast and phase contrast) modes. This novel tool was then successfully applied to a natural OC–mineral consortium from mountain soil at a spatial resolution of 60 nm, showing the fine structure and boundary of OC, the distribution of abundant nano-sized minerals, and the 3-D organo-mineral association in situ. The stabilization of 3500-year-old natural OC was mainly attributed to the physical protection of nano-sized iron (Fe)-containing minerals (Fe oxyhydroxides including ferrihydrite, goethite, and lepidocrocite), and the strong organo-mineral complexation. In situ evidence revealed an abundance of mineral nanoparticles, in dense thin layers or nano-aggregates/clusters, instead of crystalline clay-sized minerals on or near OC surfaces. The key working minerals for C stabilization were reactive short-range-order (SRO) mineral nanoparticles and poorly crystalline submicron-sized clay minerals. Spectroscopic analyses demonstrated that the studied OC was not merely in crisscross co-localization with reactive SRO minerals; there could be a significant degree of binding between OC and the minerals. The ubiquity and abundance of mineral nanoparticles on the OC surface, and their heterogeneity in the natural environment may have been severely underestimated by traditional research approaches. Our in situ description of organo-mineral interplay at the nanoscale provides direct evidence to substantiate the importance of mineral physical protection for the long-term stabilization of OC. This high-resolution 3-D tomography approach is a promising tool for generating new insight into the interior 3-D structure of micro-aggregates, the in situ interplay between OC and minerals, and the fate of mineral nanoparticles (including heavy metals) in natural environments.

A novel gold/aniline-pentamer-based electroactive polyamide (Au/EPA) composites that can modify carbon paste electrodes (CPEs) for ascorbic acid (AA) sensing has been studied in detail in this article. Cyclic voltammetry studies indicated improved electrochemical properties of the Au/EPA composites, demonstrating the occurrence of efficient electron/charge transfer between the Au and the EPA. Experimental tests shows that there is a linear relationship between the concentration of added AA and the response current for the CPE modified with Au/EPA sensor to the concentration of AA in the range of 0.05–0.75 mM (R2 = 0.996, n = 15). The detection limit and the sensitivity of the Au/EPA-CPE AA sensors were 2.75 µM at a signal to noise ratio (S/N) of 3, and 21.7 mA·mM–1, respectively.

To understand the corrosion characteristic of metal in atmospheric environment in Taiwan, Taichung Harbor was used as an example in this study, and ISO 9223 standard was followed to conduct an atmospheric corrosion deterioration factor survey and metallic exposure test for four types of screw metals: carbon steel, zinc, copper, and aluminum. The main objective of this study was to understand the classification and ranking of metallic corrosion, conduct surface analysis, examine trend change, and set up a forecasting model of metallic corrosion speed. According to the classification of ISO 9223 atmospheric corrosion of 1-year-period deterioration factor (time of wetness, chloride, and sulfur dioxide), it was found from the results that all four metals were of C4 ranks. However, for the one-year period exposure test of metal, carbon steel, copper, and aluminum can reach the C5 rank. In the trend change of 2-year metallic corrosion, for all four metals, a higher corrosion rate can be seen in the initial stage; for aluminum and zinc, a stable corrosion rate can be seen in the second month. For carbon steel and copper, a stable corrosion rate can be seen in the sixth month. In the process of setting up an artificial neural forecasting model, carbon steel and copper showed good forecasting capabilities in three models. The ANN model was suitable for zinc, while the PCA-ANN model was suitable for aluminum.

Conventional anodic aluminium oxide (AAO) was formed using direct-current anodization from high-purity (99.99%–99.999%) Al foils at low 0–5 °C with a growth rate about 2–3 μm/h. Here, we investigate the greatly enhanced growth behaviour of AAO from AA5052 Al-Mg alloy (96.6%Al-2.6%Mg) at high 25 °C using hybrid-pulse anodization. The Mg-impurity and high-temperature enhanced growth rate of AAO at 25 °C is over three-fold to 9.7 μm/h; it also reduces the average pore size to 32.2 nm from 42.8 nm due to high-activity Mg hydrolysis releasing high Mg(OH) 2 -formation heat and H 2 gas. The unique property of AAO from AA5052 is discussed.

Two dimensional (2D) vertically-aligned crystalline α-Fe 2 O 3 nano-wall arrays were prepared by thermal oxidation of iron substrates under the O 3 ambient. It is found that α-Fe 2 O 3 nano-partitions can be produced in a process temperature region of 450–500 °C. Higher growth temperatures (650–700 °C) produced wholly nanowires. The transition from 2D sheet-like nanostructures to 1D nanowires can be described by surface diffusion growth mechanism. The iron oxide nanowires present very weak magnetoresistance at different magnetic fields. However, the α-Fe 2 O 3 nano-partitions have very strong magnetoresistive properties which a high of 45% resistance variation obtained at low magnetic field of 300 Gauss. This unique property shows the potential of iron oxide nano-partition arrays in detection magnetic field and solid state memory applications.

In this article, we investigate the enhanced photoluminescence (PL) behavior of nanoporous anodic aluminum oxide (AAO) formed by one-step anodization of aluminum (Al) in oxalic acid at room temperature (25 °C) from both high- (99.99%) and low-purity (99%) Al. Compared with studies using the traditional two-step direct-current anodization at low temperature (0–10 °C), we introduce hybrid-pulse anodization to synthesize AAO from high- and low-purity Al at 25 °C for enhancing the PL. The PL intensity of high-purity AAO was stronger than the low-purity one due to the reduced surface scattering and intrinsic impurity inhibition. Besides the purity effect, AAO formed at the elevated temperature of 25 °C also greatly enhanced the PL intensity compared to that at the low temperature of 5 °C. Experimental results showed that both the high- and low-purity AAOs synthesized at 25 °C led to enhancements of the intensity of the PL peak by about 3.7–5.5-fold, depending on the Al purity and deconvoluted peak wavelength. These improvements were attributed to the high temperature enhancing the AAO thickness and reaction rate, thereby enabling more fluorescent ions to diffuse into the AAO for increased vacancy defects.

To examine the relationship between macular microvasculature parameters and functional changes in persons with diabetic retinopathy (DR).Cross-sectional study of 76 eyes with varying levels of DR. Optical coherence tomography angiography (OCTA) quantified superficial and deep perifoveal vessel densities and foveal avascular zone areas. Retinal sensitivity was measured using microperimetry. Optical coherence tomography angiography parameters and retinal sensitivity were correlated.Deep perifoveal vessel density decreased with increasing severity of DR (adjusted mean 51.93 vs. 49.89 vs. 47.96, P-trend = 0.005). Superficial and deep foveal avascular zone area increased with increasing DR severity (adjusted mean: 235.0 µm vs. 303.4 µm vs. 400.9 µm, P-trend = 0.003 [superficial]; 333.1 µm vs. 513.3 µm vs. 530.2 µm, P-trend = 0.001 [deep]). Retinal sensitivity decreased with increasing DR severity (adjusted mean: 25.12 dB vs. 22.34 dB vs. 20.67 dB, P-trend = 0.003). Retinal sensitivity correlated positively with deep perifoveal vessel density (Pearson's ρ = 0.276, P = 0.020) and inversely with superficial foveal avascular zone area (Pearson's ρ = -0.333, P = 0.010).Alterations in retinal microvasculature can be observed with OCTA with increasing severity of DR. These changes are correlated with reduced retinal sensitivity. Optical coherence tomography angiography is useful to detect and quantify the microvasculature properties of eyes with diabetic macular ischemia.

Objective Doxorubicin (DOX) is an effective anti-neoplasm drug, but the early and late cardiac toxicity limits its clinical use. The Endothelial-to-mesenchymal transition (EndMT) has been found to involve in the process of heart failure. It's unclear whether EndMT plays a role in DOX-induced cardiomyopathy (DoIC). Calcitriol is an active form Vitamin D3, which blocks the growth of cancer cells via inhibiting Smad pathway. This study investigated the cardiac protective effect of calcitriol via inhibiting of EndMT in DoIC. Methods/Findings C57BL/6 mice and endothelial-specific labeled mice were administered Dox twice weekly for 4 weeks [intraperitoneally (i.p.), 32 mg/kg cumulative dose]and were subsequently treated with/without calcitriol for 12 weeks. The cardiac echography revealed diastolic dysfunction at 13 weeks following the first DOX treatment and was accompanied by increased of myocardial fibrosis and up-regulated pro-fibrotic proteins.(Figure A-C) Calcitriol attenuated DOX-induced myocardial fibrosis, down-regulated pro-fibrotic proteinsand diastolic function. Endothelial fate tracing revealed that endothelium-derived cells contributed DOX-induced cardiac remodelling through EndMT and Calcitriol attenuated this process without attenuating Dox-induced cardiac myocyte and endothelial cell damage.(Figure D) In vitro, we examined if calcitriol would inhibit EndMT and fibroblast-to-myofibroblast transition (FMT) through the Smad pathway. Human umbilical vein endothelial cells (HUVECs) and mouse cardiac fibroblasts were treated with TGF-beta with or without calcitriol. Morphological, immunofluorescence staining, and western blot analyses were carried out to evaluate EndMT and FMT. Calcitriol attenuated EndMT and FMT by inhibiting the Smad2 pathway. Taken together, calcitriol didn't reduced Doxorubicin induced damage of cardiomocyte and endothelial cells. But calcitriol inhibit doxorubicin induced heart failure by attenuating cardiac fibrosis through inhibiting Smad pathway. Conclusion Calcitriol attenuated DOX-induced cardiomyopathy partial through inhibiting EndMT process. Acknowledgement/Funding CMRPG8E0661-3

To describe the 25-year surgical trends, long-term outcomes and risk factors affecting the outcomes of giant retinal tear-related rhegmatogenous retinal detachments (GRT-RRD). Patients’ demographics, pre-operative characteristics, risk factors, operative procedures and post-operative outcomes were collected and divided into three groups – Group A: 1991 to 2015 (overall); Group B: 1991 to 2005, and Group C: 2006 to 2015. Functional and anatomical successes were monitored over a 5-year period. Multivariate logistic regression analysis was performed to identify the risk factors related to functional and anatomical success.127 eyes of 127 patients were included in the study. At 5th year, 69.4% patients had visual acuity (VA) logMAR 1.0 (all p

Microparticles are used in a variety of different fields, such as drug delivery. Recently, non-spherical microparticle generation has become desirable. The high surface-to-volume ratio of non-spherical microparticles allows for enhanced targeting, and attachment to cells and tissue. Current non-spherical microparticle generation techniques require complicated setup, and utilizing natural micrograins, such as pollen grains, as non-spherical delivery vehicles, requires extensive post-processing. Here, we describe a unique and facile chemical synthesis approach, for controlled generation of pollen-like microparticles, based on ionic cross-linking of alginate and calcium chloride (CaCl2), within an all-biocompatible aqueous two-phase system (ATPS) of dextran (DEX) and polyethylene glycol (PEG). Our technique controls the length of spikes that emerge on the surface of these microparticles. We anticipate that these pollen-like spiky microparticles may be used as drug delivery vehicles, and this new chemical synthesis approach may be used for generating other biomaterials.

We use a novel acoustic-based flow cytometer to detect individual nanobubbles flowing in a microfluidic channel using high-frequency ultrasound and photoacoustic waves. Each individual nanobubble (or cluster of nanobubbles) flowing through the foci of high-frequency ultrasound (center frequency 375 MHz) and nanosecond laser (532 nm) pulses interacts with both pulses to generate ultrasound backscatter and photoacoustic waves. We use in-house generated nanobubbles, made of lipid shells and octafluoropropane gas core, to detect ultrasound backscatter signals using an acoustic flow cytometer. Nanobubble solutions sorted in size through differential centrifugation are diluted to 1:10,000 v/v in phosphate buffered saline solution to maximize the probability that the detected signals are from individual nanobubbles. Nanobubble populations were sized using resonant mass measurement. Results show that the amplitude of the detected ultrasound backscatter signal is dependent on the nanobubble size. The average amplitude of the ultrasound backscatter signals from at least 950 nanobubbles with an average diameter of 150 nm, 225 nm, and 350 nm was 5.1±2.5 mV, 5.3±2.3 mV, and 6.4±1.8 mV, respectively. Similarly, we detected interleaved ultrasound backscatter and photoacoustic signals from nanobubbles tagged with Sudan Black B dye. The average amplitude of the ultrasound backscatter and photoacoustic signals from these black nanobubbles with an average diameter of 238 nm is 10±11 mV and 54±75 mV, respectively. The presence of the dye on the shell suppressed unique features seen in the ultrasound backscatter from the nanobubbles without dye. At present, there is no robust commercial technique able to analyze the ultrasonic response of individual nanobubbles. The acoustic flow cytometer can potentially be used to analyze physical parameters, such as size and ultrasonic response, of individual nanobubbles.

Background Tendon stem/progenitor cells (TSPC) exhibit a low proliferative response to heal tendon injury, leading to limited regeneration outcomes. Exogenous growth factors that activate TSPC proliferation have emerged as a promising approach for treatment. Here, we evaluated the pigment epithelial-derived factor (PEDF)-derived short peptide (PSP; 29-mer) for treating acute tendon injury and to determine the timing and anatomical features of CD146- and necleostemin-positive TSPC in the tendon healing process. Methods Tendon cells were isolated from rabbit Achilles tendons, stimulated by the 29-mer and analyzed for colony-forming capacity. The expression of the TSPC markers CD146, Oct4, and nestin, induced by the 29-mer, was examined by immunostaining and western blotting. Tendo-Achilles injury was induced in rats by full-thickness insertion of an 18-G needle and immediately treated topically with an alginate gel, loaded with 29-mer. The distribution of TSPC in the injured tendon and their proliferation were monitored using immunohistochemistry with antibodies to CD146 and nucleostemin and by BrdU labeling. Results TSPC markers were enriched among the primary tendon cells when stimulated by the 29-mer. The 29-mer also induced the clonogenicity of CD146+ TSPC, implying TSPC stemness was retained during TSPC expansion in culture. Correspondingly, the expanded TSPC differentiated readily into tenocyte-like cells after removal of the 29-mer from culture. 29-mer/alginate gel treatment caused extensive expansion of CD146+ TSPC in their niche on postoperative day 2, followed by infiltration of CD146+/BrdU− TSPC into the injured tendon on day 7. The nucleostemin+ TSPC were located predominantly in the healing region of the injured tendon in the later phase (day 7) and exhibited proliferative capacity. By 3 weeks, 29-mer-treated tendons showed more organized collagen fiber regeneration and higher tensile strength than control tendons. In culture, the mitogenic effect of the 29-mer was found to be mediated by the phosphorylation of ERK2 and STAT3 in nucleostemin+ TSPC. Conclusions The anatomical analysis of TSPC populations in the wound healing process supports the hypothesis that substantial expansion of resident TSPC by exogenous growth factor is beneficial for tendon healing. The study suggests that synthetic 29-mer peptide may be an innovative therapy for acute tendon rupture.

Retinal arterioles, venules and capillaries are differentially affected in diabetes, and studying vascular alterations may provide information on pathogenesis of diabetic retinopathy (DR). We conducted a cross-sectional study on 49 diabetic patients, who underwent fundus photography and optical coherence tomographic angiography (OCT-A). Fundus photographs were analysed using semi-automated software for arteriolar and venular parameters, including central retinal arteriolar equivalent (CRAE), central retinal venular equivalent (CRVE) and fractal dimension (FD). Capillary parameters were measured using OCT-A, including capillary density index (CDI) and capillary FD of superficial (SVP) and deep (DVP) vascular plexuses. Severe DR was defined as severe non-proliferative DR and proliferative DR. We found that eyes with severe DR had narrower CRAE and sparser SVP CDI than eyes without. In logistic regression analysis, capillary parameters were more associated with severe DR than arteriolar or venular parameters. However, combining arteriolar, venular and capillary parameters provided the strongest association with severe DR. In linear regression analysis, eyes with poorer visual acuity had lower CRAE and FD of arterioles, venules, and DVP capillaries. We concluded that the retinal microvasculature is globally affected in severe DR, reflecting widespread microvascular impairment in perfusion. Arteriolar, venular and capillary parameters provide complementary information in assessment of DR.

Various digestions are available for the determination of selenium (Se) in environmental samples. This study aimed to investigate the most effective digestion method for the determination of Se in green tea samples that effective, eco-friendly, and low cost. Samples were digested with three different acid compositions, the aqua regia method (a mixture of nitric acid-hydrochloric acids HNO3-HCl) in a ratio 1:3, only nitric acid HNO3, and reverse aqua regia method (a mixture of nitric acid-hydrochloric acids HNO3-HCl) in a ratio 3:1. Analysis of Se was conducted using fluorescence spectrometry after derivation by 2,3-diamino naphthalene (DAN). The results show that the aqua regia method was the highest fluorescence intensity. It had given a significant fluorescence intensity of 9.0510 a.u. for 2 mL sample, 26.3689 a.u. for 5 mL sample, 54.4308 a.u. for 10 mL sample, respectively. In addition, the aqua regia digestion resulted in the selenium form in the sample has been converted to tetravalent selenium, and there was a silicone compound as precipitation can be found after digestion. The aqua regia method provides a highly effective digestion method for selenium in green tea samples under fluorescence spectroscopic investigation.

Purpose To prospectively evaluate whether diabetic macular ischemia detected with coherence tomography angiography (OCTA) is associated with change in functional outcomes over a period of one year. Methods This is a one-year prospective, observational study that included 56 eyes with varying levels of diabetic retinopathy. All participants underwent best corrected visual acuity evaluation, swept-source OCTA and microperimetry at baseline and repeated at one year. Parafoveal vessel densities (VD) and foveal avascular zone (FAZ) areas were generated from OCTA in the superficial and deep vascular plexuses. The influence of baseline and change in OCTA parameters on change in visual acuity and retinal sensitivity over one year was evaluated. Results Over the one-year follow-up period, 16% (9) of eyes had at least one line worsening in BCVA and 7% (4) of eyes had at least 5% decrease in retinal sensitivity compared to baseline. Diabetic retinopathy progressed in 12.5%. Mean superficial vascular plexus (SVP) FAZ area increased (0.32 ± 0.15 to 0.39 ± 0.18 mm2, P = 0.003) and parafoveal VD in deep vascular plexus (DVP) decreased (49.8 ± 3.7% to 48.8 ± 2.9%, P = 0.040) at one year compared to baseline. In the multivariate regression analysis, larger baseline DVP FAZ area was associated with worsening of BCVA over one year (β = 0.16 logMAR per mm2, 95% CI 0.02 to 0.31, P = 0.032). In addition, larger decreases in SVP VD (β = -4.18 db per 10% decrease, 95% CI -6.55 to -1.80, P = 0.002) was associated with worsening of retinal sensitivity over one year. Conclusions Progression of parafoveal microvasculature changes over one year can be detected using OCTA. Larger baseline DVP FAZ area on OCTA is predictive of worsening in visual outcomes, and larger decreases in SVP VD were associated with worsening of retinal sensitivity over a course of one year in diabetic individuals.

Grape skin and seeds contain large amounts of phytochemicals such as polyphenols, resveratrol, and proanthocyanidins, which possess antioxidant activities. Cisplatin is widely used in the treatment of cancer. High doses of cisplatin have also been known to produce acute adverse effects. The aim of this study was to investigate the protective effects of antioxidant properties of whole grape juice (with skin and seeds) on cisplatin-induced acute gastrointestinal tract disorders and nephrotoxicity in Wistar rats. Gastric emptying is significantly increased in whole grape juice-pretreated rats when compared to cisplatin treatment alone. The expression of ghrelin mRNA of stomach is increased in rats with whole grape juice. However, pretreatment with whole grape juice did not reduce renal function markers in acute renal toxicity. No significant changes were recorded in the oxidative stress/antioxidant status parameters of any study group. In contrast, pretreatment with whole grape juice slightly improved tubular cell vacuolization, tubular dilatation, and cast formation in renal tubules. These results show that consumption of whole grape juice induces somewhat beneficial effects in preventing cisplatin-mediated dyspepsia but does not offer protection against cisplatin-induced acute renal toxicity.

We present a simple microfluidic system that generates water-in-water, aqueous two phase system (ATPS) droplets, by passive flow focusing. ATPS droplet formation is achieved by applying weak hydrostatic pressures, with liquid-filled pipette tips as fluid columns at the inlets, to introduce low speed flows to the flow focusing junction. To control the size of the droplets, we systematically vary the interfacial tension and viscosity of the ATPS fluids, and adjust the fluid column height at the fluid inlets. The size of the droplets scales with a power-law of the ratio of viscous stresses in the two ATPS phases. Overall, we find a drop size coefficient of variation (CV; i.e. polydispersity) of about 10 %. We also find that when drops form very close to the flow focusing junction, the drops have CV of less than 1 %. Our droplet generation method is easily scalable: we demonstrate a parallel system that generates droplets simultaneously, and improves the droplet production rate by up to one order-of-magnitude. Finally, we show the potential application of our system for encapsulating cells in water-in-water emulsions, by encapsulating microparticles and cells. To the best of our knowledge, our microfluidic technique is the first that forms low interfacial tension ATPS droplets without applying external perturbations. We anticipate that this simple approach will find utility in drug and cell delivery applications because of the all-biocompatible nature of the water-in-water ATPS environment.

Novel high permeable porous Ni-Mo substrates with different area densities of straight gas flow channels are successfully developed to improve the hydrogen fuel gas and the water byproduct diffusion in the anode and supporting substrate. Metal-supported cell A, cell B and cell C with 5 × 5 cm2 supporting substrates are fabricated by atmospheric plasma spraying processes, these cells have the material structure of Ni-Mo/LSCM (La0.75Sr0.25Cr0.5-Mn0.5O3–δ)/NiO-LDC(Ce0.55La0.45O2–δ)/SDC(Sm0.15Ce0.85O3–δ)/LSGM (La0.8Sr0.2Ga0.8Mg0.2O3–δ)/SSC(Sm0.5Sr0.5CoO3–δ). Cell A is supported by a conventional porous Ni-Mo substrate without straight gas flow channels, cell B and cell C are supported respectively by the novel high permeable porous Ni-Mo substrates with 1.5 and 2.73 channels per square centimeter. The power densities at 0.8 V and 750 °C are 550, 998 and 1,161 mW cm−2 for cell A, cell B and cell C respectively. The 100 h durability test at the constant current density of 400 mA cm−2 and 650 °C shows cell B and cell C have smaller degradation rates than cell A. The results obtained from AC impedance and circuit model analyses indicate that the electrolyte ohm and the cathode polarization resistances are significantly reduced by introducing straight gas flow channels into the supporting substrate.

Hericium erinaceus(HE) is an edible mushroom that has been shown to exhibit anticancer and anti-inflammatory activities. We investigated the antiangiogenic and antioxidant potentials of ethanol extracts of HE in human endothelial (EA.hy926) cells upon tumor necrosis factor-α- (TNF-α-) stimulation (10 ng/mL). The underlying molecular mechanisms behind the pharmacological efficacies were elucidated. We found that noncytotoxic concentrations of HE (50–200 μg/mL) significantly inhibited TNF-α-induced migration/invasion and capillary-like tube formation of endothelial cells. HE treatment suppressed TNF-α-induced activity and/or overexpression of matrix metalloproteinase-9 (MMP-9) and intercellular adhesion molecule-1 (ICAM-1). Furthermore, HE downregulated TNF-α-induced nuclear translocation and transcriptional activation of nuclear factor-κB (NF-κB) followed by suppression of I-κB (inhibitor-κB) degradation. Data from fluorescence microscopy illustrated that increased intracellular ROS production upon TNF-α-stimulation was remarkably inhibited by HE pretreatment in a dose-dependent manner. Notably, HE triggered antioxidant gene expressions of heme oxygenase-1 (HO-1),γ-glutamylcysteine synthetase (γ-GCLC), and glutathione levels, which may contribute to inhibition of ROS. Increased antioxidant status was associated with upregulated nuclear translocation and transcriptional activation of NF-E2related factor-2 (Nrf2) in HE treated cells. Our findings conclude that antiangiogenic and anti-inflammatory activities ofH. erinaceusmay contribute to its anticancer property through modulation of MMP-9/NF-κB and Nrf2-antioxidant signaling pathways.

We demonstrate the dynamic control of aqueous two phase system (ATPS) droplets in shrinking, growing, and dissolving conditions. The ATPS droplets are formed passively in a flow focusing microfluidic channel, where the dextran-rich (DEX) and polyethylene glycol-rich (PEG) solutions are introduced as disperse and continuous phases, respectively. To vary the ATPS equilibrium condition, we infuse into a secondary inlet the PEG phase from a different polymer concentration ATPS. We find that the resulting alteration of the continuous PEG phase can cause droplets to shrink or grow by approximately 45 and 30 %, respectively. This volume change is due to water exchange between the disperse DEX and continuous PEG phases, as the system tends towards new equilibria. We also develop a simple model, based on the ATPS binodal curve and tie lines, that predicts the amount of droplet shrinkage or growth, based on the change in the continuous phase PEG concentration. We observe a good agreement between our experimental results and the model. Additionally, we find that, when the continuous phase PEG concentration is reduced such that PEG and DEX phases no longer phase separate, the ATPS droplets are dissolved into the continuous phase. We apply this method to controllably release encapsulated microparticles and cells, and we find that their release occurs within 10 seconds. Our approach uses the dynamic equilibrium of ATPS to control droplet size along the microfluidic channel. By modulating the ATPS equilibrium, we are able to shrink, grow, and dissolve ATPS droplets in situ. We anticipate that this approach may find utility in many biomedical settings, for example, in drug and cell delivery and release applications.

With the rapid development of immuno-therapy approaches for cancer treatment, tools that characterize tumor-infiltrating immune cells fuel new opportunities to better understand the natural defense mechanisms against tumor cells. The AmpliSeqTM for Illumina Immune Repertoire Plus, TCR beta SR Panel is a targeted sequencing assay that assesses T cell clonal diversity by amplifying the CDR3 region of the TCRβ gene in both DNA or RNA. This study describes the performance of this assay on peripheral blood mononuclear cells (PBMC) as high-quality input as well as formalin-fixed paraffin embedded (FFPE) samples, using the MiXCR Immune Repertoire Analyzer app for clonotype analysis. Multiple replicate libraries prepared from RNA (n=6) and DNA (n=12) extracted from the same PBMC donor showed a minimum of 96.4% alignment, with high reproducibility between replicates for clonotypes ( Citation Format: Valerie N. Montel, Stephanie B. Greene, Jeff H. Tsai. Profiling T cell clonality in FFPE samples using a targeted sequencing approach: Critical parameters and limitations [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 173.

A major barrier to the clinical utilization of microfluidically generated water-in-oil droplets is the cumbersome washing steps required to remove the non-biocompatible organic oil phase from the droplets. In this paper, we report an on-chip magnetic water-in-water droplet generation and manipulation platform using a biocompatible aqueous two-phase system of a polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer (PEG-PPG-PEG) and dextran (DEX), eliminating the need for subsequent washing steps. By careful selection of a ferrofluid that shows an affinity toward the DEX phase (the dispersed phase in our microfluidic device), we generate magnetic DEX droplets in a non-magnetic continuous phase of PEG-PPG-PEG. We apply an external magnetic field to manipulate the droplets and sort them into different outlets. We also perform scaling analysis to model the droplet deflection and find that the experimental data show good agreement with the model. We expect that this type of all-biocompatible magnetic droplet microfluidic system will find utility in biomedical applications, such as long-term single cell analysis. In addition, the model can be used for designing experimental parameters to achieve a desired droplet trajectory.

This paper presents in situ fabrication of polymeric machine elements operated by hydrodynamic forcing. With a single-step production, rotary polymer microgears are installed in microfluidic channels via UV-induced polymerization. First, a single microgear is formed, and its rotational performance is characterized as a function of the flow rate of a polymer solution. Then, the rotation of multiple microgears in a single microchannel is demonstrated, where all of the gears are driven by a single fluid flow stream. Finally, paired microgears are fabricated, and the gears show the ability to transmit torque. This ability may be integrated to build polymer microelectromechanical systems that are useful for biomedical applications.

Arsenic contamination of drinking water is a major global problem, with contamination in Bangladesh deemed most serious. Although the current World Health Organisation (WHO) maximum contamination limit (MCL) for arsenic in drinking water is 10 μg L−1, due to practical and economic constraints, the standard limit in Bangladesh and many other developing nations is 50 μg L−1. We propose that an ideal arsenic sensor, designed for routine monitoring, will have five essential qualities: sensitivity and selectivity for arsenic; speed and reliability; portability and robustness; reduced health and environmental risks; and affordability and ease of use for local technicians. It is our opinion that many of these characteristics can be accentuated by microfluidic systems. We describe candidate colorimetric, electrochemical, biological, electrophoretic, surface-sensing, and spectroscopic methods for arsenic detection; and comment on their potential for portable microfluidic adaptation. We also describe existing developments in the literature towards the ultimate creation of microfluidic total analysis systems (μTASs) for arsenic detection. The fundamental purpose of this review is to highlight the need for better portable arsenic contamination detection, and describe how microfluidic technology may be developed to address this need.

We present a technique that generates droplets using ultralow interfacial tension aqueous two-phase systems (ATPS). Our method combines a classical microfluidic flow focusing geometry with precisely controlled pulsating inlet pressure, to form monodisperse ATPS droplets. The dextran (DEX) disperse phase enters through the central inlet with variable on-off pressure cycles controlled by a pneumatic solenoid valve. The continuous phase polyethylene glycol (PEG) solution enters the flow focusing junction through the cross channels at a fixed flow rate. The on-off cycles of the applied pressure, combined with the fixed flow rate cross flow, make it possible for the ATPS jet to break up into droplets. We observe different droplet formation regimes with changes in the applied pressure magnitude and timing, and the continuous phase flow rate. We also develop a scaling model to predict the size of the generated droplets, and the experimental results show a good quantitative agreement with our scaling model. Additionally, we demonstrate the potential for scaling-up of the droplet production rate, with a simultaneous two-droplet generating geometry. We anticipate that this simple and precise approach to making ATPS droplets will find utility in biological applications where the all-biocompatibility of ATPS is desirable.

Herein, we present a microfluidic platform that generates particle-stabilized water-in-water emulsions. The water-in-water system that we use is based on an aqueous two-phase system of polyethylene glycol (PEG) and dextran (DEX). DEX droplets are formed passively, in the continuous phase of PEG and carboxylated particle suspension, at a flow focusing junction inside a microfluidic device. As DEX droplets travel downstream inside the microchannel, carboxylated particles that are in the continuous phase partition to the interface of the DEX droplets, due to their affinity to the interface of PEG and DEX. As the DEX droplets become covered with carboxylated particles, they become stabilized against coalescence. We study the coverage and stability of the emulsions, while tuning the concentration and the size of the carboxylated particles, downstream inside the reservoir of the microfluidic device. These particle-stabilized water-in-water emulsions showcase good particle adsorption under shear, while being flowed through narrow microchannels. The intrinsic biocompatibility advantages of particle-stabilized water-in-water emulsions make them a good alternative to traditional particle-stabilized water-in-oil emulsions. To illustrate a biotechnological application of this platform, we show a proof-of-principle of cell encapsulation using this system, which with further development, may be used for immunoisolation of cells for transplantation purposes.

Electrospraying is a technique used to generate microparticles in a high throughput manner. For biomedical applications, a biocompatible electrosprayed material is often desirable. Using polymers, such as alginate hydrogels, makes it possible to create biocompatible and biodegradable microparticles that can be used for cell encapsulation, to be employed as drug carriers, and for use in 3D cell culturing. Evidence in the literature suggests that the morphology of the biocompatible microparticles is relevant in controlling the dynamics of the microparticles in drug delivery and 3D cell culturing applications. Yet, most electrospray-based techniques only form spherical microparticles, and there is currently no widely adopted technique for producing nonspherical microparticles at a high throughput. Here, we demonstrate the generation of nonspherical biocompatible alginate microparticles by electrospraying, and control the shape of the microparticles by varying experimental parameters such as chemical concentration and the distance between the electrospray tip and the particle-solidification bath. Importantly, we show that these changes to the experimental setup enable the synthesis of different shaped particles, and the systematic change in parameters, such as chemical concentration, result in monotonic changes to the particle aspect ratio. We expect that these results will find utility in many biomedical applications that require biocompatible microparticles of specific shapes.

We report the fabrication of short-channel FinFETs on InGaAs-on-silicon wafers using the aspect ratio trapping (ART) technique. We demonstrate excellent short-channel control down to 20 nm gate length due to scaled fin width down to 9 nm and reduction of parasitic bipolar effect (PBE). PBE that plagues III-V NFETs with gate-all-around (GAA) or III-V-on-insulator (III-V-OI) structures can be significantly suppressed by optimized ART FinFET technology. We demonstrate record high on-current ION and low drain leakage current for short gate lengths in the 20–32 nm range for InGaAs-on-silicon NFETs.

Antrodia salmonea is well known in Taiwan as a beneficial mushroom. In the present study, we investigated the antioxidant activity of whole fermented broth (AS), filtrate (ASF), and mycelia (ASM) of A. salmonea using different antioxidant models. Furthermore, the effect of A. salmonea on AAPH-induced oxidative hemolysis of human erythrocytes and CuSO4-induced oxidative modification of human low-density lipoproteins (LDLs) was examined. We found that the AS, ASF, and ASM possess effective antioxidant activity against various oxidative systems including superoxide anion scavenging, reducing power, metal chelation, and DPPH radical scavenging. Further, AAPH-induced oxidative hemolysis in erythrocytes was prevented by AS, ASF, and ASM. Notably, AS, ASF, and ASM appear to possess powerful antioxidant activities against CuSO4-induced oxidative modification of LDL as assessed by malondialdehyde (MDA) formation, cholesterol degradation, and the relative electrophoretic mobility of oxidized LDL. It is noteworthy that AS had comparatively strong antioxidant ability compared to ASF or ASM, which is well correlated with the content of their total polyphenols. Thus, A. salmonea may exert antioxidant properties and offer protection from atherogenesis.

To describe the anatomic and functional outcomes in a cohort of subjects undergoing vitrectomy for retinal detachment (RD) resulting from myopic macular hole (MH) and to analyze the prognostic and surgical factors predicting retinal reattachment and MH closure.Retrospective case series.All patients who underwent vitrectomy for RD resulting from myopic MH between 2000 and 2009 at our center.Case records were reviewed at 6 months after surgery. Retinal reattachment and complete anatomic success, defined as retinal reattachment with MH closure, were assessed. Multivariate logistic regression models, including age, gender, duration of symptoms, spherical equivalent refraction (SE), internal limiting membrane peeling, tamponade choice, and concurrent scleral buckling, were constructed to assess associations with covariates.Retinal reattachment and complete anatomic success (retinal reattachment with MH closure).In total, 114 subjects were analyzed. Most were women (n = 79 [69.3%]), and the mean age was 57.5±13.3 years. The mean SE was -9.88±6.37 diopters. At 6 months, 98 subjects (86.0%) demonstrated retinal reattachment, of whom 93 subjects required only 1 operation. Complete anatomic success was achieved in 61 subjects (53.5%), of whom 55 needed only 1 operation. Subjects with retinal reattachment had better best-corrected visual acuity (BCVA; mean BCVA, 1.22±0.81 logarithm of the minimum angle of resolution [logMAR] units) than those without (mean BCVA, 1.98±1.26 logMAR units; P 0.001), and subjects with complete anatomic success had better BCVA (mean BCVA, 1.05±0.87 logMAR units) than those without (mean BCVA, 1.62±0.87 logMAR units; P 0.001). In multivariate analyses, increasing age and the use of perfluoropropane (C3F8) tamponade were predictive of anatomic success (per 1-year increase: odds ratio [OR], 1.049; 95% confidence interval [CI], 1.002-1.099; P = 0.04; and for tamponade: OR, 10.71; 95% CI, 1.08-106.29; P = 0.04).Vitrectomy is effective in the repair of RD resulting from MH in myopic eyes, with retinal reattachment achieved more frequently than MH closure. Retinal reattachment and MH closure are important for improving visual outcomes. Greater age at presentation and use of C3F8 are associated with a greater likelihood of anatomic success.

Succinate dehydrogenase (SDH), Ca(2+) ATPase, Lactate dehydrogenase (LDH), are involved in energy metabolism. These enzymes can be used as indicators of the energy capacity of aerobic cells. The study investigated the effects of L-carnitine supplementation on M. pectoralis superficialis, M. pectoralis profundus, M. extensor carpi radialis muscle and M. flexor carpi ulnaris. Twenty-eight racing pigeons hatched at the same time were divided randomly into three groups. Eight pigeons, which were used as the control group, were sacrificed at 92-day old. The remaining twenty pigeons continued training until they reached 157-day old, with half the pigeons getting 25 mg/head/day of L-carnitine, while the other half given the same amount of water. The pigeons were assessed by histochemical methods and reverse transcription polymerase chain reaction (RT-PCR). To assess influence of L-carnitine on muscle fibre composition and the performance of three genes' mRNA, this study applied SDH localization, SDH, Ca(2+) ATPase and LDH mRNA expression to examine the results after oral administration of L-carnitine in vivo in racing pigeons. The results showed that L-carnitine significantly elevated the amount of white muscle fibre type IIa (p < 0.05). The mRNA expression quantities of SDH and LDH gene was higher via RT-PCR method. However, the expression of Ca(2+) ATPase remains similar. In conclusion, appropriate oral administration of L-carnitine of 25 mg/pigeon/day will result in an improvement of muscles related to flying.

In the present study, the surface morphological features and nanomechanical properties of GaN and Al 0.08 Ga 0.92 N thin films are investigated by means of atomic force microscopy (AFM) and nanoindentation techniques, respectively. The GaN and Al 0.08 Ga 0.92 N thin films are deposited on c-plane sapphire substrates by using the metal-organic chemical vapor deposition (MOCVD) method. The films thickness of both GaN and Al 0 . 08 Ga 0 . 92 N thin films are about 1 μm. From AFM observations, the surface roughness of Al 0.08 Ga 0.92 N thin films is larger than GaN thin films. In addition, the hardness and Young's modulus of GaN and Al 016 Ga 0 .8 4 N thin films are measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) mode. The CSM results indicated that the values of hardness (Young's modulus) of GaN and Al 0 . 08 Ga 0 92 N thin films are about 15 GPa (240 GPa) and 17 GPa (300 GPa), respectively. Nanoindentation results exhibit the discontinuities (so-called multiple "pop-ins" event) in the loading segments of the load-displacement curves, indicative of the deformation behavior in the hexagonal-structured GaN and Al 0 . 08 Ga 0 92 N thin films is the nucleation and propagation of dislocations. Also, the micro-Vicker indentation-induced fracture patterns of GaN and Al 0.08 Ga 0.92 N thin films are clearly observed by using optical microscopy (OM). Further, the fracture toughness and fracture energy of GaN and Al 0.08 Ga 0.92 N thin films are also calculated.

Retinal angiomatous proliferation (RAP) is a unique variant of neovascular age-related macular degeneration. Published studies have estimated that up to 15% of patients with neovascular age-related macular degeneration have RAP. Clinical features frequently associated with RAP include bilateral disease, presence of pigment epithelial detachments, and reticular pseudodrusen. RAP is more frequently associated with the development of retinal pigment epithelial tears and geographic atrophy that can lead to severe vision loss. Recent advances in retinal and choroidal imaging technology have furthered our understanding of RAP. Although indocyanine green angiography remains the gold standard diagnostic tool, optical coherence tomography has improved the precision by which neovascular age-related macular degeneration with RAP lesions can be diagnosed, staged, and monitored. Anti-vascular endothelial growth factor therapy is currently the first line of treatment. Other treatment options including combination of photodynamic therapy with antiangiogenic agent intravitreal injections or corticosteroids may also achieve a reasonable therapeutic outcome; however, RAP may portend a more guarded visual prognosis than typical choroidal neovascularization because of variable treatment response and dependence on the disease stage. Future basic and clinical research is needed to clarify the pathophysiology, definition and classification, optimal treatment regimen, and long-term outcome of RAP.

Is crystalline ZnO(0 0 0 1 ¯ ) O-face surface believed to be enriched by Zn atoms? This study may get the answer. We proposed a simplified model to simulate surface concentration ratio on (0 0 0 1 ¯ )-O or (0 0 0 1)-Zn surface based on the hard-sphere model. The simulation ratio was performed by integrating electron signals from the assumed Auger emission, in which the electron mean free path and relative atomic layer arrangements inside the different polarity ZnO crystal surface were considered as relevant parameters. After counting more than 100 experimental observations of Zn/O ratios, the high frequency peak ratio was found at around 0.428, which was near the value predicted by the proposed model using the IMFP database. The ratio larger than the peak value corresponds to that observed in the annealed samples. A downward trend of the ratio evaluated on the post-sputtering sample indicates the possibility of a Zn-enriched phase appearing on the annealed O-face surface. This phenomenon can further elucidate the O-deficiency debate on most ZnO materials.